Since a previous experiment revealed that late stage pregnancy exposure of CF-1 mice to high frequency noise resulted in a significant increase in fetolethality, the hormonal/biochemical correlates of this effect are to be sought. Since corticosterone levels were measured and found to be unaffected by noise exposure, this experiment will focus on catecholamines, because exogenous introduction of these substances has been found to increase fetolethality. Exposure period will be 12 hours (noon to midnight) as before.